Persons living with HIV/AIDS are vulnerable to a range of pernicious opportunistic infections and frequently succumb to the ravages of disseminated fungal disease. New drugs to treat azole-resistant fungal pathogens and refractory infections in the central nervous system are highly desirable. Marine natural products exhibit an extraordinary chemical diversity making them ideal as sources of novel hits in cultured cell assays against Candida spp., Cryptococcus sp. and other fungal pathogens. The proposal expands a successful program in discovery, structure elucidation and biological characterization of antifungal leads from marine invertebrates with emphasis on mechanism-based screens, functional assays and mechanism of action. Achievements from the past investigations have evolved into directions towards new goals, particularly methodology for discovery of antifungal agents for emergent pathogens, for example, Cryptococcus gatti, C. neoformans, and C. gatti, with emphasis on overcoming drug resistance in the melanized growth phase. Features of the technical approaches of this proposed research include refinement of powerful tools for structure elucidation at sub- micromole scale based on integration of microcryoprobe NMR, mass spectrometry, circular dichroism and organic synthesis, and a new deep-chemical diversity 'bottom-up' (DCD-BU) approach for discovery of new chemical entities. The expected results include identification of important non-azole leads for antifungal drug development, in particular against the pathogens Cryptococcus gatti and C. grubbi, with potential of beneficial outcomes in quality of life for patients living with HIV/AIDS.